The field of small space positioning, positioning within spaces of a few meters or less, is known. Known applications utilizing small space positioning systems include applications with pointing devices for computer interaction, robotics and machine control systems, as well as computer interaction systems for toys and inventory control. Certain applications may require 2D solutions, others may require 3D solutions. Certain applications such as pointing devices may require only one-way communication, whereas others, e.g. robotic applications, may require two-way communication.
Object positioning by usage of range finding with directional transmitter/receiver is also well known using ultrasonic reflection in a method called SONAR (sound navigation and ranging). This method works similarly to RADAR (radio detection and ranging): An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to the transmitter as an echo and can be detected through the receiver path. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine how far away the object is.
International Patent Application Publication No. WO2005111653, entitled “Acoustic Robust Synchronization Signaling For Acoustic Positioning System”, assigned to Epos Technologies Ltd; Altman Nathan, the contents of which are hereby incorporated by reference, describes positional element and positioning device, wherein the positional element transmits a continuously modulated acoustic waveform and a synchronization signal that is a sequence of at least two synchronization packets, each bearing timing data for the continuously modulated acoustic waveform. Additionally, the synchronization signal uses time hopping to support concurrent positioning of a plurality of positional elements.
International Patent Application Publication No. WO03088136, entitled “Method And System For Obtaining Positioning Data”, assigned to Epos Technologies Ltd; Altman Nathan and Eliashiv Oded, the contents of which are hereby incorporated by reference, describes a positional element for attaining a position and including a first emitter for emitting a substantially continuous ultrasonic waveform decodable to fix the position, and a detector arrangement for detecting the waveform in a manner permitting fixing of the position and outputting the waveform for computation, in a manner retentive of the position fixing ability.
International Patent Application Publication No. WO2008117292, entitled “System And Method For Positioning”, assigned to Epos Technologies Ltd; Altman Nathan and Agassy Meir, the contents of which are hereby incorporated by reference, describes the usage base-band and carrier information for providing improved accuracy and/or reduced ambiguity over known systems.
“Ultrasonic Imaging in Air with a Broadband Inverse Synthetic Aperture Sonar”, Michael P. Hayes, 1997 discusses analysis of received ultrasonic reflections from digitally modulated ultrasonic signal. It lacks the technique of BB and carrier analysis, channel modeling, leakage estimation and orthogonal signals.
US2007/0121097 discusses gesture analysis using shaped ultrasonic pulse. However, the described technique uses only real signals, it does not disclose orthogonal BB signals as well as leakage estimation.
US patent application 20080005703 discloses hand gesture recognition using ultrasound. However, it does not disclose modulation techniques.
US patent application 20100296368 discloses echo analysis for gesture detection. However, it does not disclose modulation techniques neither to usage of BB and carrier information.
“Continuous Sonar Sensing for Mobile Mini Robots”, Jurgen Kalhold et al, 2002, discloses using continuous modulated transmission. However, it does not disclose usage of BB and carrier information. The discussion of orthogonal coding is for vehicles separation and for estimating the same target from several transmitters simultaneously.